import java.util.LinkedList;
import java.util.Stack;

class MyQueue {
    Stack<Integer> stack1;
    Stack<Integer> stack2;
    public int useSize;
    public MyQueue() {
        stack1=new Stack<>();
        stack2=new Stack<>();
    }
    
    public void push(int x) {
        stack1.push(x);
        useSize++;
    }
    
    public int pop() {
        if (empty()){
            return -1;
        }
        if (stack2.empty()) {
            while(!stack1.empty()){
                stack2.push(stack1.pop());
            }
        }
            return stack2.pop();
    }
    
    public int peek() {
        if (empty()){
            return -1;
        }
        if (stack2.empty()) {
            while(!stack1.empty()){
                stack2.push(stack1.pop());
            }
        }
        return stack2.peek();

    }
    
    public boolean empty() {
        return stack1.empty()&&stack2.empty();
        //return useSize==0;
    }
}